The present invention relates to a derailleur gear changing device for a bicycle shifting system, particularly a rear derailleur.
A derailleur device is known from the prior art. U.S. Pat. No. 3,973,447 specifies a derailleur device in which a chain guide device is configured having two return sprockets. By means of a fixedly disposed locating pin, it is possible to lock the chain guide device in a predetermined deflection position in relation to a movable element to which the chain guide device is pivotably fastened.
As further prior art, reference is being made to documents DE 2 153 407 A1 and DT 25 57 975 B1.
Bicycle shifting systems that provide for a sprocket cassette having a plurality of sprockets on the rear axle of a bicycle, wherein depending on the selected gear the chain is positioned on larger or smaller sprockets by means of the derailleur device are widely used and, in the meantime, have become reliable in terms of their functionality. It has become clear, however, that particularly when the back wheel is disassembled from and then reassembled with such bicycle shifting systems, such as for the purpose of repair work or for returning the bicycle from a transportation state into a ready-to-ride state, particularly “threading” the axle of the back wheel into certain receiving areas of the rear fork of the frame causes difficulties especially if a derailleur device of this kind is provided with a rear derailleur device. Due to the spring-induced holding forces that are in effect in such derailleur devices, the derailleur device moves automatically out of the starting position thereof in accordance with the holding forces during the removal of the back wheel and the sprocket cassette attached thereto. When the back wheel is subsequently reassembled, the course of the chain obstructs the assembly of the back wheel and the threading action, as indicated above, because of said starting position. In addition to threading the axle into the receiving areas of the rear fork of the frame, which is already problematic by and of itself, the derailleur device must also be deflected, counteracting the spring forces, from the starting position thereof into an operating position in order to give the chain a course that allows for the assembly of the back wheel. Simultaneously threading the rear axle into the receiving areas of the bicycle frame and positioning the derailleur device such that assembly of the back wheel is possible usually requires a certain skill level by the installer. Furthermore, said installer must also move oil-lubricated and often soiled parts therein in an effort to position the derailleur device into a position that is conducive to assembly, which is not desired. Finally, in some constructions, it is even required for the installer to touch the lubricated and typically soiled chain. An assembly of this kind is not pleasant.
The present invention addresses this problem and seeks to provide a rear derailleur device that provides for substantially easier assembly of the back wheel in contrast to the known prior art.